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Not entirely true as it does not take into account the distortion of the ball as it is compressed from front to rear by the g-forces of acceleration. This causes it to tighten against the side wall of the launch tube and create friction at the sides which adds to the distortion into a cylindrical shape for at least part of its travel down the tube.

Sounds all scientific and even believable. But the contents of a paintball are largely uncompressable. The gas pressure at the back of the ball is equally distributed and imparted on the uncompressible liquid fill which in turn pushes on the front of the shell. This all dictates that the paintball remains round. Tom Kaye has claimed high speed photography not showing deformation. I tend to beleive him, and his results coupled with the nature of the forces seem to point to a round paintball.

But that's all beside the point. What's the magical difference between open and closed bolt? In the barrel the forces are identical.

On the WARPIG experiment:

No, that is not what it proved at all. That test only proved to me that the gun was not tuned properly to maximize the potential of true closed bolt operation. If the gun was not optimized for best results in one mode, it isn't hard to see why it would show similar results in another mode.

What's the magical optimisation that will help closed bolt operation? While I respect what PPS does with markers, valves, and regulators, no hint is given here as to what magic the elves are supposed to be accomplishing. What optimisation should have been done? Why shouldn't the same optimisations be done to the open bolt?

The only "FACT" shown is that THAT gun on that day did not show a benifit to closed bolt operation. On the other hand, if the same bolt/hammer arrangement was used for both tests (closed and open bolt firing) the results would have to be the same. True closed bolt operation requires that the chambering cycle be completely seperate from the firing cycle. Bolt and hammer operating independantly. Open-bolt firing puts chambering of the round and firing it in the same move.

If you read the test descrition it seems to me the firing was separate from the chambering. In fact it would seem the gun was operated as a 'bolt action'. Meaning that any claims this wasn't 'TRUE CLOSED-BOLT' are somewhat far-fetched.

What's the magical rest time that a ball needs to recover from the 'abuse' from the bolt? Leading to the question of at what point does closed bolt, if you beleive it has an advantage, become the same as open-bolt?

Where's the proof that the bolt deforms the ball so as to affect consistency?

A barrel can only be "better" if it is different than the one it is being compared to and the best barrel for a "closed-bolt" firing gun may not be the best barrel for the same gun operating in "open-bolt" mode.

What's the magical force that makes the barrel requirements different? What are the differences that do make a barrel better?

Originally posted by Nomad Then perhaps the next Open bolt vs Closed bolt test done:

1) With an Autococker with the Firestorm Kit equipped on it.

Getting an accurate evaluation of the difference between closed and open bolt firing will depend on whether or not the hammer and bolt function independantly or connected together and functioning in unison. If the bolt and hammer are not connected and moving independantly, true open bolt firing is not being accomplished. Electronic timing of the bolt movement and hammer release can present a miss-conception of open bolt operation.

[i]
2) Using an aftermarket barrel, perhaps an Aradus as it can be adjusted for multiple bores, thus having a better chance for paint to barrel match.
[/B]

One of the biggest considerations for the consistency and accuracy of a barrel on a closed bolt firing gun is a provision for making sure that the ball stays in contact with the face of the bolt when the ball is chambered so each ball is fired from the exact same location in the barrel. A ball fired from even a little bit forward of the bolt will generally be a bit lower in velocity than one fired from a position that is tight to the face of the bolt. That is the reason that the barrels on all PPS markers (all closed bolt firing guns) are honed to an eliptical shape in the bore and have a containment system at the rear of the barrel (called the "wedgit" system) to insure consistent positioning of the ball when it is fired.

[i]
3) Using a HPA tank and another regulator (perhaps a Palmers Stabilizer and one of those AGD Flatlines. We're taking one shot at a time, shoot-down probably not a problem).
[/B]

4) Making the test in indoor conditions, to reduce the chance of wind being a factor (don't think wind can be completely eliminated in any condition).

[i]
5) Have the target at about 30 to 40 feet, to simulate normal shooting distance in a game.
[/B]

Stretch that distance out to 60 to 100 feet and you will more easily be able to measure the difference in shot pattern. Especially if the gun(s) are fired from a vise and take the shooter out of the equation.

If you accurately define the difference in operation between firing from the open bolt position and firing from the closed bolt position, you will minimize your confusion.

Originally posted by SlartyBartFast

Sounds all scientific and even believable. But the contents of a paintball are largely uncompressable. The gas pressure at the back of the ball is equally distributed and imparted on the uncompressible liquid fill which in turn pushes on the front of the shell. This all dictates that the paintball remains round. Tom Kaye has claimed high speed photography not showing deformation. I tend to beleive him, and his results coupled with the nature of the forces seem to point to a round paintball.

But that's all beside the point. What's the magical difference between open and closed bolt? In the barrel the forces are identical.

What's the magical optimisation that will help closed bolt operation? While I respect what PPS does with markers, valves, and regulators, no hint is given here as to what magic the elves are supposed to be accomplishing. What optimisation should have been done? Why shouldn't the same optimisations be done to the open bolt?

If you read the test descrition it seems to me the firing was separate from the chambering. In fact it would seem the gun was operated as a 'bolt action'. Meaning that any claims this wasn't 'TRUE CLOSED-BOLT' are somewhat far-fetched.

What's the magical rest time that a ball needs to recover from the 'abuse' from the bolt? Leading to the question of at what point does closed bolt, if you beleive it has an advantage, become the same as open-bolt?

Where's the proof that the bolt deforms the ball so as to affect consistency?

What's the magical force that makes the barrel requirements different? What are the differences that do make a barrel better?

This is my simple, no science added, total WAG, and I know that those things are not appreciated in Deep Blue.

I personally thought, as long as the valve is consistant and areas such as barrel and paint are decent, that the only other factor that could affect accuracy in the feilds of Open vs Closed bolt is the movement of the ball as the air is applied to it.

In-accuracy is from a ball incurring to much spin. You want to have a small, slight spin on the ball, just to counter static boundry affect issues (sorry to add science to a WAG), but too much spin pulls it to the side it rotates against.

Now, if a gun incurrs pre-spin on the ball, so that the ball already has spin (such as forward or 'down' spin) as the air hits it then the related spin is increased (according to this WAG.) This would be influenced by guns that had loose breeches, and had a fast cycling bolt. If the ball was able to stop completely before the air hits it, I would think that the you would loose the incurred spin. Or if the gun has a tight breech, so that the ball spin is minimised. Also for guns that had breeches that were too tight, or a barrel transition point that could also add to the spin.

But most of this is a guess. I am most likely wrong, and even not close in any manner. DO NOT TAKE THIS AS TRUTH! And there would be quite a few other issues, such as valve type and such.

I do know of a guy who has a very clean closed bolt Angel. It can be ran either Open of Closed by turning the bolt, with no difference in performance besides that. When he gets finished with it, he can do some true Open vs Closed with a little more of a top of the line gun (sorry Bill!), one that also has had a history with its accuracy and range.

Please feel free to pick this apart, thats why I dropped it here.

Josh

"If you build it they will run" - pbjosh
MM006610 bought new in '94. One owner.http://itspaintball.com For Pneu Ideas

mechanical repeatability

Paladin (all reverence due):
I am not arguing one is better than the other, I have this to pose.

If say a lapco autospirit barrel, and paint that mic's out to .688 were used.
That should ensure a tight fit in the breech for each shot.
We also assume the ball is pushed into the breech of the
barrel on this marker before air
is introduced.

What does the small amount of time that the bolt is at rest
before the valve is openned buy us?

I honestly think the debate will never end, and that marker a can be shot
as well as marker b with the
right setup. This is just
a clarification issue I think
could be interesting.

Would a pump-action Phantom with an autotrigger be an appropriate open bolt equivalent? You can cock the marker, hold down the autotrigger, and move the pump forward to fire, thus firing from an open bolt position. If you controlled the pump arm with a pneumatic ram (for more consistant shot to shot pump motion), you could operate the Phantom in either open or closed bolt mode simply by choosing whether the trigger is continually squeezed (autotrigger "open bolt mode") or only squeezed after the bolt is in the forward position (normal "closed bolt mode").

Bench mount the Phantom, clamp the trigger down, and just cycle the pump. Measure each shot's velocity. Measure the shot grouping at a fixed distance. Remove the trigger clamp, install a solenoid to move the trigger (so no hands touch the bench mounted marker during firing), and repeat the velocity and grouping test. Repeat the test as many times as you like at different target distances.

Just a thought for a reasonable open/closed bolt testbed. Feel free to hurl rotten fruit my way if you see fit to do so.

Re: mechanical repeatability

Originally posted by Paladin Sorry, but I don't deal in Magic or elves.

If you accurately define the difference in operation between firing from the open bolt position and firing from the closed bolt position, you will minimize your confusion.

With all due respect you don't get away with blithe comments in Deep-Blue (or maybe you do as you refuse to give out any technical ideas). If I'm confused it's because you're offering no new information. How about some meatier explainations?

What can be more 'true-closed bolt' than bolt action? That was how the Stingray was fired in the test.

Sounds to me that you're just arguing tiny semantics (and millionths of a second) to try a maintain a point that puts your own products in a better light.

Which is really unfortunate as there is no doubt about it, your guns are good and amongst the best. But you're not providing much in the way of proof or substance here.

Originally posted by ezrunner What does the small amount of time that the bolt is at rest before the valve is opened buy us?

And that's the million dollar question. At what rate of fire does open-bolt equal closed-bolt if you are to believe one has an advantage over the other? Under rapid fire, you're talking milliseconds between the mythical stop and stabilisation of the ball and the injection of gas.

Still waiting for some kind of proof that once jammed into a correctly sized barrel how any of the theorising of bolt/ball dynamics really has any effect.

A well tuned cocker (closed-bolt) and an XMag (open-bolt), both with the same barrel (as both are cocker threaded and use detents), shooting the same velocity, will both perform identically.

And the debate rages on..... I must say that this debate is much more enjoyable here in Deep Blue than other places where it ends up "just because!"

I would like to ask this learned group, if the debate is over which one is "better" what magnatude of "better" does it have to be to constitute proof?? If a closed bolt shoots one ball out of 1000 more accurately does that count? How about 1 in 100 or 1 in 20??

In astrophysics this is asked all the time "how do you know you really detected something?" In that field they do it statistically with either a 2 sigma or 3 sigma requirement for a clean believeable detection of difference.

Some of you must know about statistics here and understand what a 3 sigme detection means. I would sugest you argue the right protocall for a test in hopes that someone will actuall do it and put this to rest.

You question the importance of only having a few shots more accurate than open bolt.

But all of this is quite moot.

A sphere is a sphere is a sphere.

Many people have argued that the Warpig test used low-end equipment for it's open/closed bolt test. I whole heartedly agree.

But as in every test, your results must be repeatable and you must minimize your variables.

Why weren't nylon balls used? One might argue that results from using nylon would not matter because we do not use nylon balls on the field. But, when we can't have trials that aren't exactly the same, you throw the hypothesis out the window.

Now if we talk about 3 sigma, that's a whole other can of worms.

For those unfamiliar with statistics, sigma is a notation used so we can estimate the percantage of a population within a range of the median determined by sigma.

Tom, in your example of having 1 out of 100 shots more accurate than open bolt, if it is important enough. As a marketing standpoint, having even 1 out of 1000 will have a large amount of people shelling out for a new gun. As a functional standpoint, no. So where do we determine importance? If it is functional!

Three sigma is quite a large percantage of a population. Two sigma is also quite large.

Jebus, astrophysics has crazy amounts of assumptions and approximations. My physics TA was a grad student in astrophysics and told us how they make calculations where they round off a few hundred billion miles and still be okay.

At 300 fps, we have the ball terminating at a range of 118.7 feet, .427 feet high, and 138.1fps.

At 310 fps, we have the ball terminating at a range of 121.4 feet, .450 feet high, and 140.1fps.

At 290 fps, we have the ball terminating at a range of 115.9 feet, .404 feet high, and 136.0fps.

I have no clue why the ball terminates with velocity and elevation, but let's take this data as is.

Let's say our target is some dude at 118.7 feet away from us. He's sticking out his bum out the side of his bunker. At 300fps, we got him. At 310fps, the ball travels less than 3 feet more and .23 feet higher in elevation. Basically, we got him at this range too. At 290 fps, we have a similar situation where the target is large enough to tag his bum.

I took some liberty in the assumption of the ranges of the 3 velocities hitting him, but the end elevation are within .046 feet in a range of 5.5 feet. That target area is a pretty tight one.

So with a velocity fluctuation of +/-10fps, we have a pretty accurate gun. And this is for a target over 100 feet away. Would you be happy with a gun that shoots +/-10fps? It's pretty damn accurate, but it isn't a selling statistic.

So how accurate is your gun? As accurate as your shot to shot accuracy. I guess I should be asking how consistent is your gun. Consistency is key. Paintballs aren't accurate shot to shot. Once again, a sphere is a sphere is a sphere.

When a noob asks you what is the most accurate gun, you don't tell them which gun, but rather just to get a gun that will make them happy and a freak kit (Or a bore that fits their fields paint best).

I say we make a new discussion about the Advantage shell. It has a roughed up texture as compared to the other glossy smooth shells. And the stuff just SMELLS like my grandma deep frying fish in a wok of dumpster juice.

So in conclusion, I believe that there is little benefit to accuracy from improving shot to shot accuracy. The only PRACTICAL benefit I see in improving consistency is in tourney ball. A consistent gun will allow you to run a velocity as close to 300fps possible without going over and getting penalized for hot shots.

But to say neither open nor closed-bolt makes a difference we're still debating those that would have us beleive there is some magical/unexplainable force working on the ball after it leaves the barrel. But they contend that it can be optimised for.

I think accuracy, or inaccuracy, itself needs to be looked at. What causes problems, what would make one shot, not gun, more accurate than another.

Alot of people have taken the easy way out and said "all the guns firing at the same velocity shoot the same distance" but don't think that is right. Look at the Flatline barrels. That alone breaks the statement all to bits.

Look at a baseball pitcher. He can throw a ball at the same speed, but with incurred spin on a ball he can control the distance and do, well, if I could make a gun that shot like a baseball pitcher..............

With every ball, the spin it has is the ENTIRE issue with accuracy. So, if a gun, barrel, ball, magic elves, can make the ball spin at the right rate, then you can have the range and accuracy inherent in the system.

I think that some gun systems add an amount of bad spin. As I stated above some of the reasons, what needs to be put down first, above ALL the velocity issues, is SPIN.

Spin is the issue at hand, not velocity, not Closed Bolt or Open. If you can have the right about of spin you have good range and accuracy. If you have bad spin, then you don't have either.

The arguement of velocity = range does not work when shooting a round projectile. Because spin is going to affect both portions of it.

Saying the range is totally a factor of velocity puts you in the "Earth is Flat" group.

Originally posted by pbjosh Alot of people have taken the easy way out and said "all the guns firing at the same velocity shoot the same distance" but don't think that is right. Look at the Flatline barrels. That alone breaks the statement all to bits...
Saying the range is totally a factor of velocity puts you in the "Earth is Flat" group.

I think what "most" of us say/mean is that without spin, guns firing at the same velocity shoot the same distance. Sometimes we just get lazy and leave out the "without spin" part. As far as I know, NO ONE has EVER proven that anything other than spin (and velocity) affect distance and accuracy of a standard paintball.

I contend that most of our 'guns are plenty accurate considering the projectiles that we are dispensing. Someone stated in a post earlier that "a sphere is a shpere is a sphere" and that is true but I haven't seen many paintballs that are actually a true sphere. Most every paintball that I have seen and/or measured is a bit larger around or across the seem than it is when measured around or across the poles of the ball. It is also true that paintballs are filled with a material that is generally accepted as a "non compressable liquid" . Howerever, that liquid is contained in a relatively flexible container which is susceptable to distortion from the influance of the g-forces applied during the process of acceleration. Thus, when when acceleration begins, the flexibility of the shell allows the ball to tighten against the bore of the barrel and become somewhat cylindrical in shape. You can prove this out to yourselves with a very simple demonstration. Place a clean, unmarked ball in a barrel that you can blow it through with your own breath fairly easily. (a common "test" for proper bore sizing) Now blow the ball through the barrel and catch it in a soft cloth so you can inspect it closely (under magnification). After moving the ball through the barrel you will be able to see a small skid mark left on the surface of the ball; usually at two points near the seem of the ball. Now take that same ball and shoot it at game velocity through the same barrel at a bed sheet or similar hanging soft cloth that will catch the ball instead of breaking it on impact and again observe the size of the skid-mark left on the ball as it went down the barrel under pressure. You will see that the abount of shell that comes in contact with the sides of the barrel is significantly larger than when moved through the barrel with higher acceleration and g-forces. Now, the simple fact remains that the ball could not show a wider track on it unless it distorted enough to tighten the ball against the walls of the tube it is being pushed through. As the ball tightens and seals against the bore it has no choice but to become shorter in length, aka distorted by the forces of acceleration. Though not supported by a set of scientific calculations, the above demonstration and maybe a little basic comon sense, should prove to at least some of you that a paintball has to go through a lot of changes during the process of getting launched effectively. The trick to "effective" launching of a paintball is to understand that what goes on inside the barrel can and does effect what goes on shortly after the ball leaves the barrel. Internal ballistics do in fact influence external ballistics.
The most noticeable effect of improper propulsion characteristics (or tuning) is the amount of muzzle blast that can and does impart influence to the flight of a paintball AFTER it leaves the barrel. In short, the FACT of the matter is: if a mass of air blows past the not so round and somewhat flexible sphere after it has left the confines of the barrel, it can and does affect the flight of the projectile. Therefore, proper tuning and/or other means to control and minimize the muzzle blast are paramount to maximum effective range and accuracy. Proper tuning seeks maximum efficiency which in turn minimizes the effects of muzzle blast. You can also cut down on the muzzle blast effect with the application of a muzzle break to relieve and disperse excess air before the ball leaves the confines of the barrel. A short barrel with a long muzzle break (as is the case with many or most barrels these days) can and does help to compensate for an inefficient shot. That's why I started putting muzzle breaks and vented barrels on guns back in 1987.
In reference to Tom's high speed photography of many years ago, I seem to recall that was to address the condition of the ball at the point of or after leaving the barrel.
Tom, please correct me if I am wrong here. Also, is it possible that we can see some of those pics for ourselves?

If we really want to look at accuracy statistically, I already proposed a method for testing barrel length differences in another thread.

Statistics are only a guide, reality is definative.
That sort of testing was done many years ago only I did it with .5" increments of barrel length and did it with and without adjusting the valve output to accomodate the varying barrel lengths. My testing was also done at a fixed distance of 100 feet to minimize variables. The point of my tests was to establish what barrel length was needed to achieve the proper balance of efficiency and accuracy. Since the standard power source of the day was 12 gram cartridges, efficiency of the shot was very important and the first thing I noted was that as efficiency was improved, the size of the shot pattern on the target got smaller and the second notable point was that as velocity is increased, the shot pattern got larger. I also noted that a barrel that is too long suffers many of the same shortcomings in efficiency and consistency as one that is too short. Mainly due to the varibles of the painball's shape, size and weight.

In your test procedure you start with an 18" barrel and chrono the gun to 300 fps. My question is; when you cut the barrel down by 2" do you also adjust the pressure in the dump chamber to retain 300 fps or do you log the results of only cutting the barrel ? If you adjust the pressure to maintain a given velocity, you are effectively "tuning" the gun to suit the barrel; right ? If you start with an 18" barrel at 300 fps and start cutting the barrel down without making changes to the pressure or volume of gas being used to launch the ball, you should find that velocity will climb and the shot pattern will rise and get larger on the target for the first few cuts. Will you be able to understand the results ? Will you know why cutting a barrel down can often result in an increase in velocity? Are you sure that 300 fps is the best for testing since acceptable velocity limits seem to be coming down to 280-285 going on and 300 coming off? Also, for such testing purposes, you will find that the size of the shot pattern and whether the velocity goes up or down with each subseqant change will be the leading criteria for evaluation. Better effective range will only be indicated when the shot group rises on the target without changing anything other than the barrel.

But to say neither open nor closed-bolt makes a difference we're still debating those that would have us beleive there is some magical/unexplainable force working on the ball after it leaves the barrel. But they contend that it can be optimised for. [/B]

Since it seems obvious that I cannot "prove" to you that there is a benifit to closed bolt firing of a paintball (that is as opposed to traditional open-bolt firing as found in most blow-back operated guns) maybe you should present some substantiated facts that "prove" me wrong. However, you will have to change my mind and not just throw out a bunch of adversarial inuendo that would require the writing of several books to address effectively. Please keep in mind that I have a bit over 40 years of experience in dealing with guns and ballistics (internal and external ballistics) in general and nearly 20 years and tens of thousands of hours invested in finding and understanding the best way to get a paintball to go where and when I need it. On the other hand, I don't have a scientific or debating backround so I have to deal with what I know and what I see. No magic, no little elves no guessing; just a plain and simple reliance on reality.

half this thread is not about open or closed bolt, it is about people saying the guns will shoot the same distance. Spin is NOT included.

Actually I think, maybe not in this forum, but others, that it is something forgotten more than not.

And crucial to the Open vs. Closed debate.

We have gotten the knowledge that the gun will shoot the same distance shooting a ball the same speed, but, for the most part, people are still saying "Angels will shoot just as far as a Shocker because the ball leaves the barrel at the same speed." In fact a good chunk of the better brains this sport has.

And that just isn't correct. Some guns do shoot a bit further. Paint just flies into the ground when you shoot other guns. This is the way it is.

Why? Spin. Which is inherent in some guns. And the true center of this debate, NOT velocity.

Originally posted by pbjosh Personally-
Alot of people have taken the easy way out and said "all the guns firing at the same velocity shoot the same distance" but don't think that is right. Look at the Flatline barrels. That alone breaks the statement all to bits.
...

Saying the range is totally a factor of velocity puts you in the "Earth is Flat" group.

Josh

I think you'll find that the complete statement is:

"All markers shooting the same velocity shoot the same distance, except for the flatline barrels or Z-body Automag."

That's what the position has been in the umpteen other debates on this topic.

On a side note, my colleague who is heavily into firearms and shooting says that the only advantage between open and closed bolt action in a real firearm is for first shot precision/accuracy. But bolt them down to counteract the inertia of the bolt (which on an UZI approaches a couple of pounds) on an open bolt and there's no difference.

By "glossed" and "buffed" I assume you mean honed and polished. You are incorrect in this statement, the barrel was honed and polished.

That is also incorrect, the barrel is 11" long.

I'm not sure where you got the above data about the barrel used in that test. I can't find it in the article about that test, can you please point it out to me?

Which components of the barrel were variable? As far as I was able to observe, it's interior finish, length, and inner diameter remained constant through the duration of the test.

I will repeat my question from earlier, what are the criteria you place for a "good" barrel? Please, not something vague, specific criteria.

I agree a reg would have helped consistency. You would also note, that at the time of that test regs were not commonly used in paintguns.

While the consistancy may not have been easily predicted, it was recorded, and comparable in both the control, and experimental firings. That's why the chronograph was used, and why the order of firings were swapped up to take into account changes in the pressure and temperature of the CO2 tank.

See you on the field,
-Bill Mills

alright i used my friends sting ray before it was inaccurate in my mind, saw the balls going all over the palce, and the paint to barrel match was right

didnt know abonut the swaping to get the same fps for both clsoed and open

my thoughts, this is never going to be prooven either wayt, even though i slightly defended closed bolt with argueing the warpig.com test i do not think that it[closed bolt] is more accurate or less accurate or the same, i have no real results that will make my mind change at this moment, even though im neutural i still wont accept the stingray test as proof, too many varaibles to put in, (bad barrel(try a cp or something along those lines) ( bad gun, yes tons of people think "all guns shoot the same accuracy" but i think that some guns are better than others , hense the price marks

too tired after wrestling practise, proboly some typos and errors in m yrepsonse

Originally posted by _Spork_1
(bad barrel(try a cp or something along those lines) ( bad gun, yes tons of people think "all guns shoot the same accuracy" but i think that some guns are better than others , hense the price marks

I'll ask again.

Please define a "good" barrel, and what makes a barrel "crap." Since I don't believe that Dan at CP has magic dust to sprinkle on his barrels that make them good simply because they are CP barrels, how can we decide if a barrel is "good" or "crap" for a test? What are the criteria?

Originally posted by Paladin
Now, the simple fact remains that the ball could not show a wider track on it unless it distorted enough to tighten the ball against the walls of the tube it is being pushed through. As the ball tightens and seals against the bore it has no choice but to become shorter in length, aka distorted by the forces of acceleration.

I believe such wider "tracks" on the ball could also be achieved by the ball pitching and yawing during its travel down the barrel. Many have taken it as a given that the ball will face some rotation when fired - if the ball does in fact distort to this semi-cylindrical shape, such rotation would not be possible. Thus "hook" shots caused by a yawing spin couldn't happen.

I've had a look at some of the high speed video and stills Tom has taken of balls fired through a clear barrel (some is included in the Automag RT video.) If the balls are distorting, it is too insignificant to see in the photographs. An important question to which I hope Tom can supply an answer is, where those done with gelatin paintballs, or with Perfect Circle paintballs, which have a more rigid plastic shell?

Please also note, I will happily disagree with Glenn on theory or interpretation of the results of a test or experiment, but this in no way means I don't respect his viewpoint. There are a lot of people in the industry that will support a certain theory regardless of its validity, simply as a means to market their product. Basically they have a product, and whip up a theory to explain to you why it's the best in the world and you need to buy it. Glenn on the other hand, has used his theories of paintgun operation to build quality products, and is one of the few manufacturers/customizers to understand the concepts of old world craftsmanship.

Originally posted by AGD The balls in the video were run of the mill gelatin.

That's what I thought, good to hear it confirmed.

You guys keep thinking that spin has something to do with accuracy, I would like you to prove that with something other than conjecture. Linking baseballs to paintballs doesn't cut it.

AGD

I would think the most straightforward way to document its effect would be with two-tone paint, and high speed photography as you have done.

From anecdotal evidence....

The Tippmann Flatline generates spin that has a noticable effect on the trajectory of the paintball. If the Flatline is turned 90 degrees on the roll axis and fired, the ball will lob like a normal paintball trajectory, but will hook to the left or right (depending on the direction in which the 'gun was rotated).

This hooking left or right is a behavior also sometimes seen (though not as severe) when firing paintballs out of a paintgun without any spin/no-spin design features.

Comparing this and photography AGD has taken of balls that don't spin in flight and seem to "wander" randomly in the vertical and right-left axes as they travel to target, it is reasonable to believe that a yawing spin can cause a ball to drift to the left or right of the intended target, and a pitching spin will create a vertical drift vector.

Certainly, more detailed experimentation would prove or disprove this hypothesis.

As for linking baseballs to paintballs, that brings up one of my pet peeves....

The next time someone talks about how paintballs can't maintain a spin because they are full of liquid, and "proves" it by the fact that a raw egg won't spin on a table but a hardboiled one will, throw an egg at them, because they want to play egg-ball. Then spin a paintball on the table and see how it does, and explain to them that paint fill is thicker, and doesn't have an inner sac connected to the shell with elastic like tendons.

Originally posted by AGD The balls in the video were run of the mill gelatin.

Tom, I was going to ask the same question that Bill did but it seems to me that you did the high speed photography thing before you got started on the PC balls project. Is my memory serving me correctly ?
Also, what is your take on the idea that a paintball squats a bit against the force of acceleration and tightens against the bore when it is fired ? Don't we need the ball to tighten and seal against the bore if we are to expect any kind of consistency?

[i]

You guys keep thinking that spin has something to do with accuracy, I would like you to prove that with something other than conjecture. Linking baseballs to paintballs doesn't cut it.
AGD [/B]

Again, I don't know how to "prove" it but it has been my experience that the more spin seen on a ball in flight, the larger the shot group will be on target. Here, we strive to get our guns to shoot a "nuckle ball" with no spin at all. The actual flight of the ball looks a little erratic at times but they are more likely to be in a tighter group on target.
In the old days of single colored balls, it was hard to see what was going on but when we got paint with contrasting colors in/on the shell, it was much easier to see the results of our tuning process with just a few shots. If we see much spin on the ball in flight, the gun goes back to the bench to find out why and correct the problem. Oddly enough, we have found that we could minimize the amount of spin being imparted on the ball by insuring that the air flow through the valve, air passages and bolt was "clean" fast and non turbulant. Sort of like the concept of "porting and polishing" the heads on a high performance engine. Quite often, we can drastically improve on shot-to-shot consistency, efficiency and and accuracy with just a minor correction to the shape or condition of an air passage between the valve and the face of the bolt. I've seen numerous instances where 5 seconds with a Dremel tool to champher one corner of an air passage can improve velocity by 20-40 fps; which in turn means that the shot will be more efficient, the ball will get up to speed quicker, more consistent and generally more accurate.

Originally posted by Paladin
I've seen numerous instances where 5 seconds with a Dremel tool to champher one corner of an air passage can improve velocity by 20-40 fps; which in turn means that the shot will be more efficient, the ball will get up to speed quicker, more consistent and generally more accurate.

Glenn,

In a previous post you said the open/closed bolt accuracy test did not show a difference between bolt position because the test gun was not tuned for optimal closed bolt performance.

Would it not be a possibility that it's the tuning that is optimizing efficiency and consistency in the gun setup, rather than bolt position that has provided the improved performance in your experiences?

And that is just the TIP of the iceberg. We are still dealing with a ball, which at 200mph makes for alot of interesting affects moving through an atmosphere. Spin is the entire issue for accuracy and range.

Bill-

As for the egg reference, tell them to throw an egg. Does it stop spinning? I can't throw an egg far enough for it to stop spinning before it hits, but that might be me. It does slow down...........hmm...........time for testing?

Glen-

What you were doing with tuning the valve is what I was trying to do with the 'Shiva' project. I found my valve is still a bit to harsh at 160psi, but the effeciecy and accuracy are both very good. A clean tuned port makes for an accurate gun in my opinion.